1. Field of the Invention
This invention relates to a voice activated control apparatus operable to control one or more variables of a system in response to voice commands from the operator.
2. Description of the Prior Art
Speech recognition systems are capable of recognizing words spoken by human beings. Speech recognition systems are discussed in U.S. Pat. No. 4,757,541, No. 4,633,499 and No. 4,158,750. Isolated word recognition systems have been developed to recognize and discriminate isolated words ( i.e. , words separated by a pause) which have been trained into the systems. Such speech recognition devices have been summarized by D. Raj Reddy in an article entitled "Speech Recognition by Machine: A Review" published in the Proceedings of the IEEE, April 1976, page 501-531. Connected word recognition systems are capable of recognizing and discriminating individual words from spoken phrases.
It is known to use voice recognition control systems to operate computers through the use of voice commands. Such a system is disclosed in U.S. Pat. No. 4,776,016.
It is also known to use voice recognition systems to control system variables of various active systems. In U.S. Pat. No. 4,605,080, for example, a weighing scale is disclosed involving calculating functions that includes an automatic control system that can accept spoken words as input. A speech recognition system is used for processing and analyzing speech signals output by a microphone. The microphone is connected to a speech recognition computer which outputs and applies select command control signals to effect desired control functions. It is disclosed to control conveyors to place labels on containers automatically using the speech recognition system. The apparatus may be controlled to stop and start, slow down or speed up by an operator speaking the appropriate command words into a microphone.
In U.S. Pat. No. 4,641,292, an apparatus and method are disclosed for permitting human voice control of a welding system. It is disclosed that a human operator is provided with an audiotransmitter by which the operator adjusts the welding power supply through verbal commands. The verbal commands are issued by the operator and are transmitted through a receiver to a voice recognition unit. The received signal is interpreted by a computer which is electrically connected to deliver power control signals to the welding power supply and thereby adjust the power delivered to the welding torch. The operator may also issue verbal commands to start and stop an internal combustion engine which drives the welding power supply, when the engine is used.
U.S. Pat. No. 4,472,617 discloses a heating apparatus such as an electrical oven or microwave oven which includes an enclosure case having a heating chamber in which an object to be heated is placed. It is disclosed to incorporate a voice recognition circuit for recognizing voice commands of a user of the apparatus to produce a control signal which controls a releasing means to open the door of the heating apparatus.
Various voice actuation and control systems are also disclosed in U.S. Pat. Nos. 4,799,171, 4,797,924, 4,725,956, 4,717,364 and 4,482,032.
Presently known voice recognition control systems suffer from several drawbacks, however. In all systems presently available, a particular system variable, once set into movement or change can only be stopped by using a recognizable command such as the word "stop" or the word "halt". The required interpretation/recognition step introduces a delay in actually stopping the activity. This delay can be crucial when very accurate control is required. Also, an operator, when excited in an emergency situation, will often forget the particular word (e.g., "stop") required to cease an ongoing change of a system variable. By the time control of the variable is achieved, severe system damage or physical injury can occur. It is therefore desirable to develop a system which does not suffer from these deficiencies.
Moreover, systems to be controlled often have various states or positions (i.e., a certain value for one or more system variables) which are utilized often during operation of the system. It is thus desirable to enable the operator to simply define such states or positions using a simple verbal code and thereby later enable the operator to return such a specified state or position by simply uttering the verbal code.